[JITLink][MachO] Honor the no-dead-strip flag on nlist entries.

llvm-svn: 360618

diff --git a/llvm/lib/ExecutionEngine/JITLink/MachOAtomGraphBuilder.cpp b/llvm/lib/ExecutionEngine/JITLink/MachOAtomGraphBuilder.cpp
index b24b22568269723db1143ae45d4782ad43aeb432..062bbda6f2ac6eab22c1660a117ff4afe38dba16 100644 (file)
--- a/llvm/lib/ExecutionEngine/JITLink/MachOAtomGraphBuilder.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/MachOAtomGraphBuilder.cpp
@@ -252,15 +252,22 @@ Error MachOAtomGraphBuilder::addNonCustomAtoms() {
 
     DA.setCallable(*SymType & object::SymbolRef::ST_Function);
 
-    // Check alt-entry.
+    // Check NDesc flags.
     {
       uint16_t NDesc = 0;
       if (Obj.is64Bit())
         NDesc = Obj.getSymbolTableEntry(SymI->getRawDataRefImpl()).n_desc;
       else
         NDesc = Obj.getSymbolTableEntry(SymI->getRawDataRefImpl()).n_desc;
+
+      // Record atom for alt-entry post-processing (where the layout-next
+      // constraints will be added).
       if (NDesc & MachO::N_ALT_ENTRY)
         AltEntryAtoms.push_back(&DA);
+
+      // If this atom has a no-dead-strip attr attached then mark it live.
+      if (NDesc & MachO::N_NO_DEAD_STRIP)
+        DA.setLive(true);
     }
 
     LLVM_DEBUG({

diff --git a/llvm/test/ExecutionEngine/JITLink/X86/MachO_x86-64_relocations.s b/llvm/test/ExecutionEngine/JITLink/X86/MachO_x86-64_relocations.s
index 568faebd9651d9d25c7679795840a75219c0618a..c1792f65b8ba1e08b7435158f2e808986225e92c 100644 (file)
--- a/llvm/test/ExecutionEngine/JITLink/X86/MachO_x86-64_relocations.s
+++ b/llvm/test/ExecutionEngine/JITLink/X86/MachO_x86-64_relocations.s
@@ -272,6 +272,15 @@ subtractor_with_alt_entry_subtrahend_quad_B:
         .section        __DATA,__nds_test_sect,regular,no_dead_strip
         .quad 0
 
+# Check that unreferenced local symbols that have been marked no-dead-strip are
+# not dead-striped.
+#
+# jitlink-check: *{8}section_addr(macho_reloc.o, __nds_test_nlst) = 0
+        .section       __DATA,__nds_test_nlst,regular
+        .no_dead_strip no_dead_strip_test_symbol
+no_dead_strip_test_symbol:
+        .quad 0
+
 # Check that explicit zero-fill symbols are supported
 # jitlink-check: *{8}zero_fill_test = 0
         .globl zero_fill_test